It might actually be fun to custom build a "boombox" with a large-capacity power source, something like a Radiosophy cheapie radio, a small "Class T Amplifier" from someone like Sonic Impact. This amp would be fun for any project-tinkerer to get his hands on
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-958 and since it's already designed for battery operation, it's perfect for a God-awful, ugly as sin, impractically huge kit. Add some speakers, a custom case, and you have a conversation-starter (and probably ender, as psople stare).